Year	Number
1980	5425
1982	10129
1983	10513
1984	10510
1985	9802
1986	11807
1987	14912
1988	15109
1989	15728
1990	16711
1991	13363
1992	22237
1994	15696
1996	16251
2001	26128
2002	20423
2003	28317
2004	35626
2005	30734
2006	36644
2007	32181
2008	33555
2009	37759
2010	43269
2011	50653
2013	44288
2014	34521
2015	37090
2016	48756
2017	51918